Apparatus for forming brake-drums.



, J. R. WINTER. APPARATUS F 0 R F 0 R M l N G B R A K E D R U M S.

1,272,751. Patented July 16, 1918.

the form.

UNIT TAE% PATET @FFIQE.

JOHN R. WINTER, OF DETROIT, MICHIGAN, ASSIGNOR TO KELSEY WHEEL COMPANY,

015 DETROIT, MICI-IIGAN, A CORPORATION OF MICHIGAN.

APPARATUS FOR FORMING BRAKE DRUMS.

Specification of Letters Patent. Patented July 16,1918.

Application filed August 31, 1914. Serial No. 859,569.

To all whom it may concern:

Be it known that I. JOHN R. \VINTER, a citizen of the United States of America, residing at Detroit, in the county-of I'Vayne and State of Michigan, have invented certain new and useful Improvements in Apparatus for Forming Brake-Drums, of which the following is a specification, reference being had therein to the accompanying drawings.

The invention relates to apparatus for forming brake drums and it is the object of the invention to provide means for forming from a circular blank of sheet metal a drum having a true cylindrical flange free from wrinkles and of uniform hardness and density.

In the drawings: c p A Figure l is'a cross section through the drawing dies in initial position when the flat blank has just been inserted;

Figs. 2, 3 and a are similar views showing different stages in the operation; and

F ig.'5 is a diagrammatic plan view showing respectively in full and dotted lines the effect on the metal drawn by my improved apparatus and as previously drawn.

In the fashioning of sheet metal into cylindrical or" cup-shaped form various methods have heretofore been employed. One method'is the frictional holding of the marginal portions of the blank during the initial cuppin operation to produce a drawing effect ant to prevent the formation of wrinkles. This has the disadvantages: first, that'it greatly increases the strain upon the metal during drawing; second, that the metal is elongated and correspondingly thin in section; and third,-that it is difficult to entirely avoid the formation of wrinkles.

Another method employedis the drawing of the blank'by a series of different operations, each one of which partially changes natural flow of the metal, and without the formation of any wrinkles or other irregu- The disadvantages of this method larities which would distort the form from that of a true cylinder.

A is the plunger die and B is the socket die, in which the sheet metal is fashioned. The die A is of true cylindrical form, being provided with a rounded edge C at its lower end, and the die B has the cylindrical finishing portion D concentric with the cylinder A and spaced therefrom equal to the gage or thickness of the drawn metal. Beyond the portion D the die B is enlarged and the cross sectional contour of this portion is the determining factor in the production of a drawn article free from wrinkles. Thus if the die B were provided merely with a flaring mouth of uniform taper to the cylindrical portion D, this would invariably result in producing in the blank during the initial operation wrinkles which could not be eliminated subsequently. I have discovered, however, that by changing the contour as hereinafter set forth, all wrinkling or distortion is avoided.

I As shown in Fig. 1, the die B is provided with a top face E upon which the marginal portion of the circular blank F rests. The mouth of the recess is rounded at G and then extends substantially a cylinder H to a point I, from which it extends angularly at J to a rounded K connecting with the cy lindrical portion D. The proportion and relative angles of these surfaces is such that during initial operation, as shown in Fig. 2, the blank'is drawn by the tensioning plunger A over the rounded edge G to form a cone, as indicated at L, and the contraction in the peripheral length of the blank is so limited as to avoid wrinkling. After the blank is thus formed into '-the cone, this cone is pressed down within the die without further contraction in diameter of its outer edge while said edge is traveling over the cylindrical surface H.- During this portion of the operation the descending plunger A forces the lower end of the cone past the rounded portion K and into the cylindrical portion D and the operation of forming the completed cylinder is initiated. This continues until the conical blank is forced against the tapering or conical surface J of the die. after which it will be progressively .drawn inward over the rounded edge K without distortion.

From the above description it will be observed that with my improved apparatus the operation is varied from that diagrammatically illustrated by the dotted lines in Fig. In the latter the drawing of the blank toward the cylindrical form is continuous from the beginning to the'completion of the operation and the resulting upsetting of the metal and rapid contraction in the peripheral diameter produces the wrinkled or wavy line M. This cannot be completely taken out by the subsequent operation of the cylindrical portions of the dies, and moreover the metal is unequally stressed in the crest and hollo\\'s of the wave, producing unequal wearing quality. With my improved apparatus, after the initial coning of the blank its marginal portion is permitted to remain uncontracted in diameter while the small end of the cone is being changed into its final cylindrical form. and after a portion is thus formed. into the true cylinder the flaring portion will be drawn in without tendency to buckle or to assume a distorted form. i

What I claim as my invention is 1. An apparatus for forming true cylindrical flanges on flat circular blanks, comprising a plunger for fitting the finished cylinder, and a recessed die having a finishin cylindrical portion for cooperating with said plunger, an enlarged mouth portion of -a diameter relative to that of the circular blank, such as to form an nnwrinkled conical. flange on said blank when drawn therein, and a portion intermediate of said mouth portion and finishing cylindrical portion of a cross sectional contour permitting the in-' ner end of the conical flange to be drawn into said finishing cylindrical portion while the periphery of said flange remains temporarily uncontracted in diameter.

2. An apparatus for forming true cylindrical flanges on flat circular blanks, comprising a plunger for fitting the finished cylindrical flange, and a recessed die having a finishing cylindrical portion for cooperat-' mg with said plunger and mouth portion, of a diameter relative to that of the circular blank, such as to form an unwrinkled conical flange 011 the blank when drawn in to said mouth portion, and a portion intermediate of said mouth portion and finishing cylindrical portion of a cross sectional contour having a portion substantially parallel to the plunger and an oblique portion extending from said parallel portion to said finishing cylindrical portion.

3. An apparatus. for forming true cylindrical flanges on flat circular blanks, comprising a plunger for fitting the finished cylinder, and a recessed die having a cylindrical finishing portion cooperating .with said plunger, a mouth portion of lesser diameter than the circular blank and substantially cylindrical, and an oblique or conical portion connecting said cylindrical mouth portion with said finishing cylindrical portion.

4. An apparatus for forming true cylindrical flanges on flat circular blanks, comprising a plunger and a recessed die memher having a finishing cylindrical portion, a rounded mouth portion of lesser diameter than that. of the circular blank and such as to form an unwrinkled conical flange on said blank when drawn therein, a substantially cylindrical portion extending inward from said mouth portion, and an oblique. portion connecting said cylindrical portion with said finishing cylindrical portion. be-

ing of lesser depth than theinwardly formed. conical flange, whereby the inner end of said conical flange is re-fashioned by said finishing cylindrical portion while the periphery of said flange is traversing said cylindrical mouth portion.

In testimony whereof I atfix my signature in presence of two witnesses.v

JOHN R. \VINTER. Witnesses PHYLLIS COBURN, JAMES P. BARRY. 

